Numerous substances have been disclosed in the art as effective peroxygen bleach activators. Among the best known of these are the substituted and unsubstituted carboxylic acid ester bleach activators.
U.S. Pat. No. 3,130,165, Brocklehurst, issued Apr. 21, 1964, describes a household laundry detergent composition. This composition contains a detergent, from 3-20% by weight of an inorganic peroxy-compound, and from about 0.5 to about 2.5 moles of a phenol (or substituted phenol) ester of alpha-chloro-acetic or -propionic acid per mole of available oxygen.
Detergent Age, July, 1967, describes chloroacetyl salicylic acid as an activator for low temperature perborate/peroxide bleaching.
U.S. Pat. No. 3,075,921, Brocklehurst, et al., issued Jan. 29, 1963, discloses 2-chloro, 4-chloro, and 2-methoxy peroxybenzoic acid. These acids are described as providing excellent bleaching activity when incorporated into solid detergent compositions.
British Patent Specification No. 864,798, published Apr. 6, 1961, discloses bleaching compositions comprising an inorganic persalt combined with an organic ester of an aliphatic carboxylic acid. The addition of these esters to the wash solution is said to give a more vigorous bleaching action than the hydrogen peroxide alone. Such a system therefore permits low-temperature bleaching (50.degree.-60.degree. C.) under otherwise normal washing conditions. It is preferred that the ester be derived from an aliphatic carboxylic acid having not more than 10, and preferably less than 8, carbon atoms. The patentee states that such bleaching compositions are stable during storage.
British Patent Specification No. 836,988, published June 9, 1960, describes bleaching and detergent compositions containing an inorganic persalt and an organic carboxylic acid ester. It is alleged that such esters provide improved bleaching at temperatures between 50.degree. to 60.degree. C. when compared to systems employing the persalt alone. Specific examples include sodium dodecyl benzene sulfonate and sodium dodecyl phenyl acetate.
It is also known that bleach activators which exhibit surface activity can be used in combination with peroxygen-type bleaches to provide particularly effective surface bleaching. U.S. Pat. No. 4,283,301, Diehl, issued Aug. 11, 1981, discloses bleaching compositions comprising a peroxygen bleach, such as persalt, and a bleach activator. The activators described are esters of either an alkyl mono- or di-carboxylic acid. These activators may be represented by the general formula: ##STR1## wherein R is an alkyl chain containing from about 5 to about 13 carbon atoms, R.sup.2 is an alkyl chain containing from about 4 to about 24 carbon atoms, and Z is a leaving group. The patentee states that the selected bleach and bleach activator are preferably present in equimolar ratios.
U.S. Pat. No. 4,412,934, Chung, et al., discloses bleaching compositions containing a peroxygen bleaching compound and a bleach activator of the general formula: ##STR2## wherein R is an alkyl group containing from about 5 to about 18 carbon atoms with the longest linear alkyl chain being from about 6 to about 10 carbon atoms; L is a leaving group. It is further required that the conjugate acid of the activator must have a pK.sub.a in the range of from about 6 to about 30. The molar ratio of the hydrogen peroxide generated:activator must be greater than about 1.5:1.
Certain benzene sulphonate compounds with an alkoxy group substituted on the ring are known to be useful in cleaning compositions. U.S. Pat. No. 3,685,127, Boldingh, et al., issued Aug. 22, 1972, describes detergent compositions with improved bleaching capability containing (1) an inorganic persalt, (2) an organic detergent and (3) a bleach precursor having the general formula: ##STR3## wherein X is a branched or straight chain alkyl or alkanoyl radical containing 6 to 17 carbon atoms, R is hydrogen or an alkyl radical having 1 to 7 carbon atoms, and M is an alkali metal or ammonium radical. Spray-dried detergent compositions containing 2-acetoxy-5-nonyl benzene sulfonate are disclosed.
Certain alpha-chloro and alpha-alkoxy acid esters are known to be useful as perfumes in cleaning compositions. For example, U.S. Pat. No. 3,368,943, Gilbert, issued Feb. 13, 1968, discloses compounds of the formula: ##STR4## wherein a is 0 or 1; X is chlorine or bromine; R is methyl or ethyl; and R' is a saturated C.sub.4 -C.sub.12 aliphatic branched or linear chain, benzyl, phenol ethyl, or phenol propyl radical. The compounds described by the patentee are said to possess an agreeable odor. These compounds include alpha-alkoxy isobutyrates and alpha-halo beta-alkoxy isovalerates. As perfumes, these compounds are said to be particularly suitable for use in detergents and "bleaching-aid" compositions. Cleaning compositions, detergent compositions, and bar soap compositions perfumed with these compounds are disclosed.
Poly-alpha-chloro acrylic acid is disclosed in the art as being useful in detergent compositions as both an oxidizing agent and as a thickener. British Patent Specification No. 1,420,468, published Jan. 7, 1976, suggests that oxidizing agents can be generated in a wash solution if the original detergent compositions contain a combination of sodium perborate and a poly-alpha-hydroxy acrylic acid, a poly-alpha-chloro acrylic acid, or a derivative of these compounds.
U.S. Pat. No. 3,553,140, McCrudden, issued May 15, 1979, discloses certain carboxyl-group-containing polymers useful as thickeners in detergent compositions which additionally contain a perborate. Alpha-chloro acrylic acid in a detergent composition is specifically disclosed.
U.S. Pat. No. 3,969,257, Murray, issued July 13, 1976, suggests that acetyl salicylic acid is useful as an activator for soluble peroxide bleaching agents in detergent compositions.
While the overall efficacy of carboxylic acid ester bleach activators most similar to those of the present invention is unquestioned, these art-disclosed compounds most similar to those of the present invention suffer from one significant drawback: they yield compounds (the active component) which possess a particularly repugnant odor under actual usage conditions (pH, temperature, etc.). Because they possess this odor under actual wash conditions, their overall utility and value is greatly reduced.
The malodor associated with these compounds (the active component) is well-known in the art. See "Organic Peroxides and Peroxy Compounds", Kirk-Othmer Encyclopedia of Chemical Technology, 17, 60.
U.S. Pat. No. 4,009,113, Green, et al., issued Feb. 22, 1977, discloses granular compositions comprising from about 40% to about 80% of a bleach activator and an inert carrier material such as long chain fatty acids or esters wherein said precursor is substantially evenly distributed with said precursor compound to form a composite particle. The particle has an outer protective layer which can consist of, for example, polyvinyl alcohol. It is stated that such compositions have both good storage stability and dispersibility in the wash water.
U.S. patent application Ser. No. 362,812, Gray, et al., filed Mar. 29, 1982, discloses a detergent additive composition comprising from about 75% to about 95% of a particulate infusible solid having a particle size distribution such that at least about 50% thereof passes a 250 micrometer screen and comprising storage sensitive detergent additive materials, and from about 5% to about 25% of ethoxylated nonionic surfactants melting in the range of from about 20.degree. C. to about 60.degree. C. wherein said composition is prepared via a radial extrusion process. It is stated that such compositions have improved storage stability together with excellent release and dispersibility characteristics in wash water.
U.S. patent application Ser. No. 433,499, Chung, filed Oct. 8, 1982, "Bodies Containing Bleach Activator", describes stable compositions employing binder and enrobing materials similar to those of the present invention. These compositions contain 4-(alkanoyloxo)benzenesulfonates.
It has now been discovered that certain alpha substituted derivatives of the C.sub.6 -C.sub.18 carboxylic acid esters provide particularly effective peroxygen surface bleaching performance but do so without generating the malodor associated with the use of corresponding unsubstituted or shorter chain (art-disclosed) compounds.
It has also been discovered that these alpha substituted C.sub.6 -C.sub.18 carboxylic acid esters, while very reactive, can be stabilized for storage by forming bodies containing the esters and select binder or enrobing materials, such as sorbitan esters.
It has further been discovered that these alpha substituted C.sub.6 -C.sub.18 carboxylic acid esters can be simply prepared under anhydrous conditions without generating noxious products.